Legend

With 8gb GDDR5 memory modules coming sometime this year I don't want a 256 bit bus, but a Kaveri version that can handle GDDR5. 4GB should be "easy" to fit on a mobo and it would allow for cheap, small factor PC with sane gaming possibilities

With 8gb GDDR5 memory modules coming sometime this year I don't want a 256 bit bus, but a Kaveri version that can handle GDDR5. 4GB should be "easy" to fit on a mobo and it would allow for cheap, small factor PC with sane gaming possibilities

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Does Kaveri really need 4 GB of VRAM? Taking into account the class of GPU and that the vast majority of gaming with Kaveri will be at 768p or possibly 1080p if we take desktop into account..I doubt anything more than 2 GB would be useful. Of course I'm not taking marketing into consideration...

PS: I am not fully up to date with this thread so this might sound like a noob question..but can Kaveri's MC actually support GDDR5? I remember there was a reference to a Quad channel MC/GDDR5 support in some docs earlier..but was this actually implemented in the final shipping hardware?

VeteranSubscriber

Does Kaveri really need 4 GB of VRAM? Taking into account the class of GPU and that the vast majority of gaming with Kaveri will be at 768p or possibly 1080p if we take desktop into account..I doubt anything more than 2 GB would be useful. Of course I'm not taking marketing into consideration...

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It's an APU, it also needs non-graphics RAM. It may not need more than 2GB for graphics alone, but lacking support for 8GB (or more) of RAM would be a serious limitation.

Legend

Indeed I do not get your comment either Erinyes or it is the other way around.
I'm not hoping for Kaveri to be linked (at the same time) to both DDR3 and GDDR5 but use GDDR5 as the only type of RAM
I think that you read my post as such. I agree with you based on your premise you don't need 4GB of VRAM.

Regular

It's an APU, it also needs non-graphics RAM. It may not need more than 2GB for graphics alone, but lacking support for 8GB (or more) of RAM would be a serious limitation.

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Sorry I should have clarified..I was thinking of a dedicated VRAM for the GPU alone..something along the lines of the sideport in 780G. So a 128 bit GDDR5 bus for the GPU and a 128 bit GDDR3 bus for the CPU. But you are right of course..if it was for the whole APU..I think it would have to be 8 GB or higher. 4 GB would not be enough.

Indeed I do not get your comment either Erinyes or it is the other way around.
I'm not hoping for Kaveri to be linked (at the same time) to both DDR3 and GDDR5 but use GDDR5 as the only type of RAM
I think that you read my post as such. I agree with you based on your premise you don't need 4GB of VRAM.

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Yes I should have clarified that I meant a dedicated VRAM. Like I said above..say a 128 bit GDDR5 bus for the GPU and a 128 bit GDDR3 bus for the CPU. But you are right..that is never going to happen. Even GDDR5 seems very unlikely IMHO. However Carizzo should have support for DDR4 and should bring a significant increase in bandwidth.

VeteranRegular

Sorry I should have clarified..I was thinking of a dedicated VRAM for the GPU alone..something along the lines of the sideport in 780G. So a 128 bit GDDR5 bus for the GPU and a 128 bit GDDR3 bus for the CPU. But you are right of course..if it was for the whole APU..I think it would have to be 8 GB or higher. 4 GB would not be enough.

Yes I should have clarified that I meant a dedicated VRAM. Like I said above..say a 128 bit GDDR5 bus for the GPU and a 128 bit GDDR3 bus for the CPU. But you are right..that is never going to happen. Even GDDR5 seems very unlikely IMHO. However Carizzo should have support for DDR4 and should bring a significant increase in bandwidth.

Newcomer

They are just sharing a single physical pool, but logically it is not unified. For instance, there is still a private GPU aperture in Kaveri like its brothers. Moreover, speaking of compute, although there is hUMA in HSA, HSA is not prohibiting this from happening as far as I know. HSA has the support of acquiring device local memory, which is only visible to the device, for advanced uses. Perhaps in the future, applications can even acquire coherent device memory, but so far I didn't see it in anywhere but patents.

In the foreseeable future, HBM is likely insufficient to be the system memory in terms of its capacity. So heterogeneous memory in APU is the probably only and the easiest way to go after, if one wants to scale the APUs further.

LegendVeteran

Indeed I do not get your comment either Erinyes or it is the other way around.
I'm not hoping for Kaveri to be linked (at the same time) to both DDR3 and GDDR5 but use GDDR5 as the only type of RAM

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Just saying, as a remainder : GDDR5M memory was cancelled, which was to be on SO-DIMM slots and thus precisely what's needed by Kaveri. It would have allowed to put a choice of 4GB or 8GB I think (or half that if you're dumb enough to put one stick in)

ModeratorVeteran

But equivalent Intel CPU+discrete GPU are more expensive and have more total power consumption.

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For more "premium" laptops the i7-4xxxHQ chips w/ Iris Pro outperform the 7600P and don't need the higher-bandwidth DRAM. They are somewhat higher TDP chips (47W), but have much faster CPUs and a slightly faster GPU.

On the price side they are almost certainly more expensive, but I'd caution you about "tray" prices... most major OEMs have their own pricing deals so those numbers are only really indicative in a relative sense between different SKUs, not absolute. It's also not straightforward to compare how they affect the BOM of a system since different chips require different supporting components (ex. Haswell has integrated voltage regulators). Certainly you can find these chips in $1000 laptops, albeit not $500 ones.

I agree that the 7600P is one of the more interesting Kaveri chips though. But realistically the space of ~cheapish laptops w/ relatively stronger iGPUs is a fairly niche one at the moment (you don't see a lot of Iris Pro chips outside of Apple either) for whatever reason.

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